This invention relates to a sealing structure for an adjusting ring in a clutch.
Clutches are known in the prior art wherein levers selectively force drive and driven discs into contact in order to transmit drive from a flywheel to a driven shaft. A flywheel ring or clutch cover rotates with the flywheel, and an adjusting ring attached to the clutch cover provides an abutment face to properly position the levers relative to the other members of the clutch. The primary purpose of the adjusting ring is to compensate for wear on the drive and driven discs by varying the position of the levers.
Typically, the adjusting ring is cylindrical, and has a threaded outer peripheral surface with respect to a center axis of the ring, which mates with a corresponding cylindrical threaded inner peripheral surface of the clutch cover. When the adjusting ring is rotated relative to the cover, it moves in an axial direction and the levers are repositioned accordingly.
In the prior art, the mating threads on the adjusting ring and clutch cover, hereinafter the adjustment threads, are exposed to contaminants and rust forming moisture. The contaminants include particulate matter generated from within the clutch as the discs wear. As a result of the contaminants and rust, the threaded surfaces between the adjusting ring and the flywheel housing may sometimes bind.
To reduce the friction opposing the relative rotation of the adjusting ring and clutch cover, the mating adjustment threads have typically been lubricated with a material such as grease. While lubrication initially improves operation, lubricants have tended to evaporate over time. Further, if too much lubricant is used, it may escape from the threaded area, which is undesirable.